Pulsation-damping structure for hydraulically propelled boats



March 19, 1968 J. T. YEAGER, SR

PULsATIoN-DAMPING STRUCTURE FOR HYDRAUL'ICALLY PROPELLED BOATS Filed July 13, 1965 ATTORNEYS United States Patent Ofice 3,373,565 Patented Mar. 19, 1968 3,373,565 PULSATION-DAMPING STRUCTURE FR HYDRAULICALLY PROPELLED BOATS Joseph T. Yeager, Sr., Mercer County, NJ. (37 Stevenson Ave., Trenton, NJ. 08619) Filed July 13, 1965, Ser. No. 471,616 Claims. (Cl. 60-222) This invention relates to an improved ship propulsion means, and more particularly to a propulsion means of the jet type, wherein water and air under pressure are expelled from a suitable conduit, in such fashion as to propel the vessel in a forward (or, if desired, in a reverse) direction.

One important object is to provide a propulsion means as stated that will be usable in conjunction with a ship propulsion device of the type disclosed and claimed in my copending application Ser. No. 568,202 filed July 27, 1966, as a continuation-impart of my earlier filed application Ser. No. 428,464 tiled Jan. 27, 1965 (now abandoned).

Referring to the drawings:

FIGURE l is a view partly in longitudinal section and partly in side elevation, of an air intake unit embodied in the propulsion means constituting the present invention; and

FIGURE 2 is a view partly in longitudinal section and partly in side elevation of the propulsion means, the hull of the ship being shown fragmentarily and in section.

Referring to the drawing in detail, an air intake unit generally designated includes an elongated intake tunnel or conduit 12 having a forward end 14 open to provide an entranceway 16 for air, covered by a screen 18 constituting a lter means to prevent foreign material from entering the conduit 12.

The conduit tapers toward its rear end, imparting to air owing therethrough a venturi effect. At the outlet end 20 of the conduit, the conduit is connected to a duct 22 extending to an air compression compartment 24 (FIG- URE 2). A check valve 26 permits air to ow into compartment 24, -but prevents back flow through duct 22, thus maintaining compression within compartment 24. Compartment 24 is mounted in the aft portion 28 of the boat hull 30.

Forcing of air through duct 22 to compartment 24 is effected 'by tandem air impellers 32, 34 spaced axially of their associated drive shaft 36, which is journalled in bearings 38, 40, 42 mounted in the air tunnel or conduit 12. The impellers may be of any suitable design, and in the illustrated example are provided with peripherally located, pitched blades 44, 46 respectively. It is mainly important that when shaft 36 is driven, as for example by belt and pulley means 48, air is to be drawn into the conduit, through the air intake signed to prevent back ow of air past either of the impellers. In other words, impeller 32 moves the air into the portion o-f the tunnel disclosed between impellers 32, 34. Part of this air is directed through impeller 34, being forced thereby rearwardly into ducts 22. The remaining air which was moved into the area between the impellers passes through bypasses 50 angularly spaced 90 degrees apart about the interior of the conduit. These bypasses direct air past the periphery of the rear impeller 34, and the air so directed joins the air passing through the rear impeller.

The result is that there is a flow of air through ducts 22 to compartment 24.

Belt and pulley means 48, it may be noted, are driven by shaft 52 which would be rotated by a suitable prime mover such as an internal combustion engine, not shown.

16, under circumstances de- Referring now to FIGURE 2, the reference numeral 54 designates a duct the inlet end of which would be connected to a propulsion device such as disclosed and claimed in my copending application Ser. No. 568,202. As set forth in that application, water is forced under pressure into duct 54, owing rearwardly therein.

Duct 54 extends directly through compartment 24, and has Ibleeder ports 56 communicating with the interior of compartment 24.

Duct 54, at its rear or outlet end, is connected in communication with a correspondingly inclined duct extension 5S which tapers slightly in the direction of its outlet end 60, thereby imparting to the water forced therethrough a slightly increased velocity as it is discharged below water level L. y

Pivotally connected to the duct extension 58 is a diverter hood 62 of quadrantal form. Hood 62 is movable between opposite extreme positions one of which is a lower position shown in dash-lines in FIGURE 2, and the other of which is a forward, inoperative position shown in dash-dotted lines in the same figure of drawing. When the hood is in its dash-line position, it is disposed directly in back of the outlet end 60 of duct extension 5S, as a result of which water forced out of the duct extension is diverted Iforwardly by the hood, whereby to cause the boat to move in reverse. When, on the :other hand, the hood is in its full line position, it is located for forward movement of the vessel. When the hood is in its dash-dotted position, the boat is ybeginning to move forwardly but is not yet planing.

Designated at 64 is a primary compartment, and communication is provided between the compartment 24 and the compartment 64 through the provision of ports or orifices 66 formed in the Vbottom of the compartment 24.

In use, as disclosed in my copending application Ser. No. 568,202, water is forced into the duct 54, by the device shown in said copending application, with relatively little or no surge or pulsation of the flow. In this connec tion, the compartment 24, and the air forced thereinto through duct 22, serve to further prevent pulsation or pounding Water forced through the duct 54 is permitted to pass through the ports 56 into the compartment 24, so as to be trapped within said compartment. Overflow is permitted from compartment 24 into the primary compartment 64,

Within compartment 24, further, air is present under pressure, having been directed thereinto through duct 22. A tendency either of water or air to flow upwardly through duct 22 is prevented by means of the gate or check valve 26.

By permitting the water to pass into the compartment or well 24 `through ports 56, and by maintaining a head of com-pressed air within said compartment, I provide insurance against pulsation, vibrations, and loss of continuity of propulsion while getting the boat into motion initially. The provision of a compressible fluid within compartment 24, that is, the air directed thereinto through duct 22, further serves to relieve the wall of the compartment 24 o-f undue strains that might tend to rupture the same. Such tendency toward rupture might otherwise occur within the compartment 24, should water would be forced under considerable pressure through duct 54 and ports 56 into the compartment or well 24.

In these circumstances, water will be caused :to flow as a jet out of the duct extension 58 to assure the forward propulsion of the vessel.

I claim:

1. A boat propulsion mechanism comprising:

(a) an elongated duct mountable in a boat hull, said duct having an intake end connectable to a source of water under pressure and an underwater outlet through which water forced under pressure through the duct may issue as a propelling jet;

(b) a compartment extending about the duct for part at least of a length of the duct, said duct having ports in tree communication with the compartment, said compartment constituting means into which Water may ow from the duct, and from which water may return to the duct through said ports, to provide substantially surge-free, continuous water movement through the duct; and

(c) means to direct air under pressure into said compartment, and to maintain the air so forced under compression against water owing into the compartment through said ports, whereby to relieve strain upon the compartment walls and further reduce surge and pulsation of water owing through the duct, said means to direct air under pressure into said compartment including an air conduit disposed above Water level and having an intake and an outlet, means within said air conduit for eiecting flow of air through the conduit inlet to the outlet, an air duct connected between the outlet of the conduit and said compartment, and gate valve means arranged to permit ow of air from the air duct into the compartment, While preventing back ow of air from the compartment through the air duct.

2. A boat propulsion mechanism as in claim 1, wherein the means for effecting the ow of air through the conduit comprises impellers mounted in said conduit and spaced longitudinally thereof, said conduit including bypasses extending about the impeller nearer the outlet of the conduit whereby air forced through the conduit by the impeller nearer the air intake of the conduit may in part by-pass the impeller nearer the conduit outlet, and in remaining part ow through said impeller nearer the conduit outlet, the air flowing through said by-pass merging with air passing through the impeller nearer the air conduit outlet for passage through the air tube to the compartment.

3. A boat propulsion mechanism as in claim 2 wherein said conduit is progressively reduced in cross section in a direction from the intake thereof to its connection to the air duct.

4. A boat propulsion mechanism comprising:

(a) an elongated duct mountable in a boat hull, said duct having an intake end connectable to a source of water under pressure and an underwater outlet through which 'water forced under pressure through the duct may issue as a propelling jet;

(b) a compartment extending about the duct for part at least of the length of the duct, said duct having ports in free communication with the compartment, said compartment constituting means into which water may ow from the duct, and from which water may return to the duct through said ports, to provide substantially surge-free, continuous water movement through the duct; and

(c) means to direct air under pressure into said compartment and to maintain the air so forced under compression against water flowing into the compartment through said ports, whereby to relieve strain upon the compartment walls and further reduce surge and pulsation of water flowing through the duct, comprising an air intake unit including a continuous air passage having at one end an air intake open to atmosphere and having at its other end an outlet through which air passing through said unit may ow into the compartment, a gate valve arranged to permit flow of air from the air passage into the compartment While preventing back flow of 'air from the compartment through the air passage, at least one impeller mounted in said passage for drawing air thereinto through the intake and for forcing lthe air through the passage into said compartment, and means for driving the impeller.

5. A boat propulsion mechanism as in claim 4 wherein the cross sectional area of said passage is smaller at said outlet thereof than at the location in the passage at which the impeller is mounted, to increase the velocity of the air ow at its point of entry into the compartment above its velocity at the location of the impeller.

References Cited UNITED STATES PATENTS 632,662 9/1899 Tatharn 60-221 2,696,077 12/1954 Goodman 60-222 2,712,831 7/1955 Day 138-26 3,052,093 9/ 1962 Keneck 60-221 X 3,148,745 9/1964 Jones M 181-47-.1 X 3,253,568 5/1966 Cannizzaro 11S-1l 3,266,733 8/1966 Goehler 60-221 X CARLTON R. CROYLE, Primary Examiner.

MILTON BUCHLER, Examiner.

T. M, BLIX, Assistant Examined 

1. A BOAT PROPULSION MECHANISM COMPRISING: (A) AN ELONGATED DUCT MOUNTABLE IN A BOAT HULL, SAID DUCT HAVING AN INTAKE END CONNECTABLE TO A SOURCE OF WATER UNDER PRESSURE AND AN UNDERWATER OUTLET THROUGH WHICH WATER FORCED UNDER PRESSURE THROUGH THE DUCT MAY ISSUE AS A PROPELLING JET; (B) A COMPARTMENT EXTENDING ABOUT THE DUCT FOR PART AT LEAST OF A LENGTH OF THE DUCT, SAID DUCT HAVING PORTS IN FREE COMMUNICATION WITH COMPARTMENT, SAID COMPARTMENT CONSTITUTING MEANS INTO WHICH WATER MAY FLOW FROM THE DUCT, AND FROM WHICH WATER MAY RETURN TO THE DUCT THROUGH SAID PORTS, TO PROVIDE SUBSTANTIALLY SURGE-FREE, CONTINUOUS WATER MOVEMENT THROUGH THE DUCT; AND (C) MEANS TO DIRECT AIR UNDER PRESSURE INTO SAID COMPARTMENT, AND TO MAINTAIN THE AIR SO FORCED UNDER COMPRESSION AGAINST WATER FLOWING INTO THE COMPARTMENT THROUGH SAID PORTS, WHEREBY TO RELIEVE STRAIN UPON THE COMPARTMENT WALLS AND FURTHER REDUCE SURGE AND PULSATION OF WATER FLOWING THROUGH THE DUCT, SAID MEANS TO DIRECT AIR UNDER PRESSURE INTO SAID COMPARTMENT INCLUDING AN AIR CONDUIT DISPOSED ABOVE WATER LEVEL AND HAVING AN INTAKE AND AN OUTLET, MEANS WITHIN SAID AIR CONDUIT FOR EFFECTING FLOW OF AIR THROUGH THE CONDUIT INLET TO THE OUTLET, AN AIR DUCT CONNECTED BETWEEN THE OUTLET OF THE CONDUIT AND SAID COMPARTMENT, AND GATE VALVE MEANS ARRANGED TO PERMIT FLOW OF AIR FROM THE AIR DUCT INTO THE COMPARTMENT, WHILE PREVENTING BACK FLOW OF AIR FROM THE COMPARTMENT THROUGH THE AIR DUCT. 